Getting most derived type of object that implements interface

[Kagamin via Digitalmars-d-learn]

Cast it to Object:
	FooInterface a = new BarImplementsInterface();
	FooBaseClass b = new BarDerivedClass();
	Object o = cast(Object)a;
	writefln("a class: %s", a.classinfo.name);
	writefln("b class: %s", b.classinfo.name);
	writefln("o class: %s", o.classinfo.name);